Flexible Pipe for Offshore and Other Applications

ABSTRACT

A flexible pipe for conducting fluid, such as offshore production fluids, has interior tubing, a series of rings and clamps, and exterior tubing. The interior tubing has an extruded tube and a surrounding layer. Outer rings dispose about the interior tubing and abut end-to-end. Inner rings dispose on the tubing and fit in between each of the outer rings. These inner rings have tapered surfaces that fit against beveled ends defined in each end of the outer ring&#39;s internal bore. The clamps affix the abutting ends of the outer rings together, and the exterior tubing disposes on the series of rings and clamps. This exterior tubing has an inner layer of wrapped tape surrounded by an extruded tube. A flange couples by an end clamp to the end ring of the pipe, and inner and outer supports on the flange support the interior and exterior tubing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 12/546,195, filed 24Aug. 2009, which is a continuation-in-part of U.S. application Ser. No.12/042,406, filed 5 Mar. 2008, to which priority is claimed for both andwhich are both incorporated herein by reference in their entireties.

BACKGROUND

Flexible pipe can be used for fluid transport in various areas, such asconducting production fluids offshore. For example, FIGS. 1A-1B show aflexible pipe 10 similar to that designed by Deepflex, Inc. of Houston,Tex. and disclosed in U.S. Pat. Nos. 6,491,779 and 7,254,933. The pipe10 can be used in deep sea operations such as disclosed in U.S. Pat. No.7,073,978. In general, the pipe 10 can have internal diameters of 2, 4,6, 8, or even up to 16-inches. From inside to outside, the flexible pipe10 has a number of layers, including a liner layer 11, pressurereinforcement layers 12, hoop reinforcement layers 13, a membrane 14,tensile reinforcement layers 15, and an external jacket 16.

The liner layer 11 is composed of extruded thermoplastic, such as HDPE,PA-11, PVDF and XLPE, and the membrane 14 is made of extrudedthermoplastic to seal against compressive loads from external seawaterpressure. On the outside, the external jacket 16 is made of extrudedthermoplastic to provide external protection to the pipe 10.

Internally, wraps helically wound about the pipe 10 form each of thereinforcement layers 12, 13, and 15. These wraps are made of compositematerial bonded and stacked together to form composite tapes. As theirnames imply, the pressure layers 13 are wound for external pressureloads, and the tensile layers 15 are wound for tensile loads. Likewise,the hoop layers 13 are wound for compressive loads.

Because flexible pipes can be used in conditions having high internaland/or external pressures, any rupture in one of the layers such as thepipe's inner layer can allow pressurized fluid to leak through to othersurrounding layers. If those surrounding layers have gaps in them suchas formed by wrapped tapes, then nothing essentially keeps thepressurized leak from reaching even more layers of the pipe.

SUMMARY

A flexible pipe is used to conduct fluids, such as production fluids inoffshore applications. The flexible pipe has interior tubing, a seriesof rings and clamps, and exterior tubing. The interior tubing defines abore therethrough for conducting the production fluid. The interiortubing can have an extruded tube with the bore for conducing fluid andcan have an outer layer surrounding the extruded tube. The exteriortubing can have an extruded tube disposed about the rings and clamps andcan have an inner layer of wrapped or woven material disposed betweenthe extruded tube and the rings and clamps.

The rings and clamps can be composed of metal. The rings include aseries of inner and outer rings alternatingly disposed on the interiortubing. For example, the outer rings dispose about the interior tubingand abut end-to-end. The inner rings dispose on the tubing and fitbetween each of the outer rings. These inner rings have tapered surfacesthat fit against beveled ends defined in each end of the outer ring'sinternal bore. As an alternative to metal inner rings, bands, wrappings,or the like composed of a thermoplastic or other material can fitbetween beveled ends of the outer rings.

The clamps affix the abutting ends of the outer rings together, and theexterior tubing disposes on the series of rings and clamps. Each of theclamp portions has a first end with an interior facing notch and asecond end with an exterior facing notch. When fit together, the firstends mate with the second ends, and fasteners can be used to couple thefit ends together. In use, the rings and clamps permit tilting betweeninterconnected ones of the rings so the pipe can be bent and flex in theoffshore environment.

A flange couples by an end clamp to the end ring of the pipe, and innerand outer supports on the flange support the interior and exteriortubing. The inner support disposes inside the interior tubing and hasone end engaging inside a bore of the flange. The outer support disposesoutside the exterior tubing and has one end coupled to the flange.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a perspective view of a flexible pipe according tothe prior art showing the various layers.

FIG. 1B illustrates a cross-sectional view of the flexible pipe of FIG.1A.

FIG. 2A illustrates an end view of a flexible pipe according to thepresent disclosure.

FIG. 2B illustrates a cross-sectional view of the flexible pipe of FIG.2A showing the various layers.

FIG. 2C illustrates an isolated portion of the flexible pipe'scross-section showing details of the various layers.

FIGS. 3A, 3B, and 3C illustrate an end view, a cross-sectional view, anda detailed view of a central ring for the flexible pipe's ringed layer.

FIGS. 4A, 4B, and 4C illustrate an end view, a cross-sectional view, anda detailed view of an end ring for the flexible pipe's ringed layer.

FIG. 5 shows the wall of the flexible pipe as bent.

FIG. 6 shows example thicknesses of the flexible pipe's layers.

FIG. 7 shows an end of the flexible pipe connected to an end connector.

FIG. 8A illustrates a perspective view of another flexible pipeaccording to certain teachings of the present disclosure.

FIG. 8B is a cross-sectional view of the flexible pipe in FIG. 8A.

FIG. 9A is a cross-sectional view of the flexible pipe without certaincomponents.

FIG. 9B is a perspective view of components of the flexible pipe.

FIG. 9C is an end view of layers for the flexible pipe.

FIGS. 10A-10B illustrate a cross-section and a perspective view of anend flange for the flexible pipe.

FIG. 11 illustrates a cross-section of an inner support for the flexiblepipe.

FIG. 12 illustrates a cross-section of an outer support for the flexiblepipe.

FIG. 13 illustrates a cross-section of an inner ring for the flexiblepipe.

FIGS. 14A-14B illustrate a cross-section and a detailed view of an endring for the flexible pipe.

FIG. 15 illustrates a cross-section of an intermediate ring for theflexible pipe.

FIGS. 16A-16E illustrate front, side, top, bottom, and detailed views ofa component of an end clamp for the flexible pipe.

FIG. 16F illustrates another front view of the end clamp components ofFIGS. 16A-16E connected together.

FIGS. 17A-17D illustrate front, side, top, and bottom views of acomponent of an intermediate clamp for the flexible pipe.

FIGS. 18A-18C illustrate front, side, and top views of a component ofanother clamp for the flexible pipe.

FIG. 18D illustrates another front view of the clamp components of FIGS.18A-18C connected together.

FIGS. 19A-19B illustrate side and front views of a component of yetanother clamp for the flexible pipe.

FIG. 19C illustrates another front view of the clamp components of FIGS.19A-19B connected together.

FIG. 20A illustrates a side view of three clamps for affixing ringstogether.

FIG. 20B illustrates a side view of a solitary clamp for affixing ringstogether.

FIG. 21 shows a cross-section of the flexible pipe 300 during bending orflexing.

FIGS. 22A-22B show details of the flexible pipe 300 in an initial stateand in a bent or flexed state.

DETAILED DESCRIPTION

A. Flexible Pipe Having Internal Layer, Interlocking Rings, and ExternalLayer

A flexible pipe 20 shown in FIGS. 2A-2C can be used to convey fluids,such as production fluids in offshore application, although the flexiblepipe 20 can be used in other application. The flexible pipe 20 has aplurality of layers, including from inside to outside: a liner layer 30,a first tensile layer 40, a ringed layer 50, a second tensile layer 80,and an external jacket 90. The liner layer 30 is an extruded tube madeof a plastic material, such as a composite thermoplastic or the like.Choice of the particular material depends on the intended use of thepipe 20. In one example, the liner layer 30 is composed of extrudednylon and Fortron® polyphenylene sulfide (PPS) (a high performancethermoplastic).

The ringed layer 50 is composed of a plurality of interlocking rings60/70 discussed in more detail later. The external jacket 90 is composedof a hard plastic material for protection. For example, the jacket 90can be composed of a nylon material, such as Ultramid® polyamide (nylon)from BASF Corporation for resistance to abrasion, corrosion, and hightemperature (ULTRAMID is a registered trademark of BASFAktiengesellschaft Corporation of Germany), although other materials canbe used.

As their names imply, the tensile layers 40 and 80 provide tensilestrength to the flexible pipe 20 as well as strength againstinternal/external pressure loads. Both tensile layers 40 and 80 arepreferably strong enough to carry longitudinal (tensile) stresses up to25-kpsi along the axis of the pipe 20. In the present arrangement and asbest shown in FIG. 2C, each of the tensile layers 40/80 can be composedof several layers, including an extruded tube 42/82, a reinforcementlayer 44/84, and a surrounding hard shell 46/86. Although two tensilelayers 40/80 are shown in the present arrangement, other arrangementsmay have only one tensile layer either inside or outside the ringedlayer 50. In addition, although the tensile layers 40/80 are shownhaving three layers, other arrangements may have more or less layers.

In the current arrangement, the extruded tubes 42/82 can be composed ofa hard plastic material, such as a similar thermoplastic to the linerlayer 30. The reinforcement layers 44/84 have fiber or wire woven orwrapped on the extruded tubes 42/82 to provide tensile strength to thepipe 20. These layers 44/84 can be composed of a heat-resistant andstrong synthetic fiber, such as an aromatic polyamide (“aramid”) (onetype of which is Kevlar®), or can be composed of metal wire. (KEVLAR isa registered trademark of E. I. du Pont de Nemours and Company. Thesurrounding shells 46/86 can be a hard plastic material extruded aroundthe reinforcement layer 44/84.

As best shown in FIG. 2C, the ringed layer 50 is comprised of a seriesof interconnecting rings, including central rings 60 and an end ring 70as shown. Each of the central rings 60 interlock end to end to oneanother in an interlocking arrangement that still allows for bending ortilting between the rings 60 when the pipe 20 is flexed or bent. The endring 70 interlocks at one end to a central ring 60 and has a terminatedend that does not interlock with another ring.

The rings 60/70 can be composed of metal or composite material. Forexample, each of the rings 60/70 can be cast of 17-4 stainless steelwith electroless nickel/fluoropolymer coating (e.g., Xylan®—a registeredtrademark of Whitford Corporation of West Chester, Pa.) for rustprevention. Alternatively, the rings 60/70 can be composed of acomposite material, such as carbon-fiber or glass reinforced plastic,fiber thermoplastic, or thermoplastic formulated with metal powder,although other materials are also possible depending on the desired useof the flexible pipe 20. Due to the reinforced strength of these rings60/70, the flexible pipe 20 can preferably withstand inside and outsidepressures better than a flexible pipe composed entirely of extruded orwrapped layers, yet still provide the flexibility needed for the pipe 20to be used in various applications, such as deep sea oil production.

Assembly of the pipe 20 is as follows. The liner layer 30's extrudedplastic tube is formed with the desired internal bore diameter and wallthickness for the particular implementation. In one arrangement, thefirst tensile layer 40 is independently formed as a unit having itsthree layers 42/44/46 and having a suitable internal bore diameter andwall thickness and is fit over the liner layer 30. In anotherarrangement, the extruded tube 42 of the first tensile layer 40 isindependently formed and fit onto the liner layer 30 or is extrudeddirectly onto the liner layer 30, then the woven layer 44 is formed ontothe outside of this extruded tube 42, and finally the outer shell 46 isextruded over the entire assembly.

With the first tensile layer 40 completed, the various rings 60/70 arepositioned over the first tensile layer 40 in interlocking arrangement.Naturally, the first tensile layer 40's outer diameter and the ring60/70's internal diameters are configured to fit together. The rings60/70 may be wrapped with tape or the like to hold them together duringassembly. Next, the second tensile layer 80 having its three layers82/84/86 and having a suitable internal bore diameter and wall thicknessis positioned or formed over the rings 60/70. As before, the secondtensile layer 80 can be independently formed as a unit and fit over therings 60/70, or the separate layers 82/84/86 can be separatelypositioned or formed on the assembly. Finally, the external jacket 90 isextruded on the outside of the entire assembly to complete the pipe 20.

As discussed above, the ringed layer 50 has several interconnectingcentral rings 60—an example of which is shown in more detail in FIGS.3A-3C. The central ring 60 has an external diameter D₁, an internaldiameter D₂, and a length L₁. For a flexible pipe 20 with an internalbore of about 6-inches, the ring 60's external diameter D₁ can be about8.885-inches, the internal diameter D₂ can be about 8.135-inches, andthe length L₁ can be about 4.000-inches. Because these and other valuesdisclosed herein pertain to a flexible pipe 20 with about a 6-inchinternal diameter, it is understood that the various values for thepipe's components will differ for different diameter pipes and forparticular implementations.

One end of the ring 60 has a circumferential lip 62, while the other endhas a circumferential slot 64. When rings 60 couple end to end, thecircumferential lip 62 interconnects with a circumferential slot 64 onan adjacent central ring 60. In the exemplary dimensions, the lip 62defines an overall diameter D₃ of about 8.595-inches, and the slot 64defines an overall inner diameter D₄ of about 8.575-inches.

Because the rings 60 fit together and are intended to tilt relative toone another, the circumferential lip 62 defines an outer profile 63 asshown in FIG. 3C for fitting and moving against a complementary innerprofile 65 of the circumferential slot 64. The outer profile 63 extendsa length L₂ of about 0.630-inches, while the inner profile 65 extends alength L₃ of about 0.625-inches. In addition, the lip 62 defines anangular slant θ₁ outward of about 2.65-degrees, while the slot 64defines an angular θ₂ slant inward of about 1.94-degrees. Furthermore,the lip 62's outer edge defines a radius R₁ of 0.096-inches, and itsinner edge defines a radius R₂ of about 0.096-inches. Likewise, theslots 64's inner edge defines radius R₃ of 0.091-inches, and its outeredge defines radius R₄ of 0.096-inches.

As shown in FIGS. 4A-4C, the end ring 70 is very similar to the centralring 60 discussed above. For example, the end ring's circumferentialslot 74 is essentially identical to the central ring 60's slot 64 ofFIGS. 3A-3C having dimensions L₂, R₃, R₄, and θ₂ SO it can interconnectwith a central ring's circumferential lip 62. The ring's other end 72,however, is terminated and has no slot or lip. Although not shown, anopposite end ring for the flexible pipe can similarly be made forfitting on an opposing slot 64 of a central ring 60 of FIGS. 3A-3C andcan have a terminated end and a lipped end with dimensions L₁, R₂, R₃,and

The rings 60/70 with the associated dimensions discussed above enablethe interconnected rings 60/70 to be bent or tilted relative to oneanother by about 1.5 degrees for every 4-inches (i.e., about 1.5-degreesfor every length of ring in the flexible pipe 20). For example, FIG. 5shows a wall of the flexible pipe 20 as bent with each of the centralrings 60 tilted at about 1.5-degrees relative to one another.Preferably, gaps G that may occur between the rings 60 where theyinterconnect are minimal, and sharp edges on the rings 60 are avoided.The other layers 30/40/80/90 being composed of materials such asplastic, fiberglass, composites, etc., readily flex with the bending ofthe pipe 20.

Various dimensions for the pipe's layers 30/40/50/80/90 have beenprovided above for illustrative purposes. As shown in FIG. 6 and in thetable below, the layers 30/40/50/80/90 in general have wall thicknessesthat make up the following example percentages of a flexible pipe'soverall wall thickness in which the pipe has about a 6-inch internalbore:

TABLE Each Layer's Percentage of Overall Pipe Wall Thickness WallThickness Percentage of Overall Layer (inches) Pipe Wall Thickness30—Inner Layer T₁ = 1.3 31% 40—First Tensile layer T₂ = 0.95 22% 50—RingLayer T₃ = 0.75 18% 80—Second Tensile layer T₄ = 0.75 18% 90—ExternalJacket T₅ = 0.46 11% All Layers T₀ = 4.0 100%

The above dimensions are provided merely for illustrative purposes. Itwill be appreciated that the various thickness of the layers will dependon the needs of a particular implementation, including, for example,pressure levels, tensile strength, length of the pipe, intended use ofthe pipe, materials selected, etc.

The flexible pipe 20 can be used with end connectors such as disclosedin co-pending U.S. application Ser. No. 11/961,709 entitled “EndConnector for Flexible Pipe,” which is incorporated herein by referencein its entirety. FIG. 7 shows an end of the flexible pipe 20 connectedto one such end connector 200 of the incorporated application. As shown,the end connector 200 has an outer housing 202 and inner components 204,both of which are essentially the same as those disclosed in theincorporated application. As part of the inner components 204, lockscomprising nuts and sleeves (270/275 and 290/295) mechanically grip thepipe 20's tensile layers 40/80 against an insert 280. In addition, theinsert 280's end fits against the terminated end 72 of the end ring 70.

The flexible pipe 20's other layers 30/90 are handled in similar ways tolike layers described in the incorporated application. For example, atubular insert 250 fits within the inner surface of the liner layer 30,which also has an inner nut 290 positioned against part of its outersurface. Elsewhere along the pipe 20, another lock 260 threads into aportion of the connector 200's outer housing 202 and grips against thepipe's external jacket 90.

As disclosed above, the pipe 20 of FIGS. 2A-2C has five layers30/40/50/80/90. However, variations of the disclosed flexible pipe 20are possible. For example, the flexible pipe 20 can be composed of moreor less layers depending on the implementation. In one variation, theflexible pipe 20 may include tensile layer 40, ringed layer 50, andtensile layer 80 with either one or both of the liner layer 30 andexternal jacket 90 not included. In another variation, one of thetensile layers 40 or 80 may not be included in the pipe 20.Alternatively, one of the tensile layers 40 or 80 may not have multiplelayers and may simply include an extruded tube of plastic material. Inother words, the flexible pipe 20 can at least include at least onefirst layer, a ringed layer 50 having interconnected rings (e.g., 60/70)disposed about the at least one first layer to provide strength to thepipe 20 against pressure loads, and at least one second layer disposedabout the ringed layer 50, wherein at least one of the first or secondlayers provides tensile strength to the flexible pipe 20.

B. Flexible Pipe Having Interior Tubing, Abutting Rings and Clamps, andExterior Tubing

Another flexible pipe 300 according to certain teachings of the presentdisclosure illustrated in FIG. 8A has a pipe section 302 and a flangedend 304. The pipe section 302 will typically have another flanged end(not shown) on its distal end. As before, the flexible pipe 300 can beused to conduct production fluids offshore, although the flexible pipe300 can be used for other purposes as will be appreciated with thebenefit of the present disclosure. To conduct production fluidsoffshore, for example, the flexible pipe 300 can be used for jumpers,flow lines, risers, or other conduits used in offshore production, andthe particular lengths and dimensions of the pipe 300 will depend on thedesired implementation. As a flow line, for example, the length of theflexible pipe 300 from one flanged end 304 to the other may be about1-km or the like, although any desired length could be used depending onthe implementation.

1. Components and Construction of Flexible Pipe

The end of the flexible pipe 300 is shown in cross-section in FIG. 8B,and various components of the pipe 300 are best seen in FIG. 9A-9C,which omits certain components. As shown, the pipe section 302 hasinterior tubing 400, exterior tubing 450, and a series of rings 340/360and clamps (380) disposed therebetween. The flanged end 304 has a flange310, an inner tubular support 320, an outer tubular support 330, an endring 350, and an end clamp 370.

Looking first at the pipe section 302, the interior tubing 400 definesan internal bore for conducting fluid and can have one or more layers.As shown in the end view of FIG. 9C, the interior tubing 400 has threeinner layers 402, 404, and 406, although any number of layers could beused depending on the implementation. In one arrangement, the interiortubing 400 is a spoolable reinforced composite (SRC) pipe similar tothat available from Future Pipe Industries. The first inner layer 402 isan extruded liner for conducting fluid and can have a suitable wallthickness for the implementation. This first layer 402 is composed of acomposite thermoplastic, such as high-density polyethylene (HDPE),cross-linked polyethylene (PEX), or Polyamide (Nylon) 11 (PA-11),although the actual material used depends on the intended use of thepipe 300.

The second inner layer 404 can be an overwrapping layer of a compositelaminate that provides a degree of stiffness and strength to the tubing400. For example, this second layer 404 can be composed of E-glass fiberand/or carbon fibers disposed in an amine cured epoxy. The third layer406 can be an optional lining for protecting the interior tubing 400 fortransport and assembly and for providing a tolerance layer in theassembly.

As noted previously and as shown in FIG. 8B, the pipe section 302 alsohas a series of successively abutting rings (340/360) disposed about theinterior tubing 400 and extending along the length of the flexible pipe300. The rings include inner rings 340 and intermediate outer rings 360.

To assemble the pipe section 302, an intermediate ring 360 fits on theoutside of the interior tubing 400, and an inner ring 340 fits on theinterior tubing 400 and abuts the beveled opening in the intermediatering 360. The inner ring 340 can define an axial slit (not shown)allowing the ring 340 to be flexed open slightly to help in positioningit on the tubing 400. This slit may also provide benefits in the flexingof the pipe section 302 as described in more detail later.

Continuing with the assembly of the pipe section, another intermediatering 360 fits on the interior tubing 400 and abuts the inner ring 340and the end of the adjacent intermediate ring 360. At this point, anintermediate clamp 380 affixes onto the abutting intermediate rings 360to hold them together. The assembly of the rings 340, 360 and the clamps380 then continues along the length of the interior tubing 400. Whendone, a series of inner rings 340 and intermediate rings 360alternatingly fit and abut adjacent one another along the length of theinterior tubing 400, and intermediate clamps 380 hold the abutting rings360 together.

Although use of the inner rings 340 is preferred, alternativearrangements of the pipe section 302 may not use these inner rings 340.In such an instance, the intermediate rings 360 may be disposed on theinterior tubing 400 alone and clamped together using the clamps 380. Therings 360 may still have their beveled ends as shown or may have more orless perpendicular edges suitably rounded to remove sharp edges.Moreover, if the rings 360 have beveled edges and are used bythemselves, other devices such as bands, wrappings, or the like composedof thermoplastic, elastomer, or other suitable material can be disposedbetween the abutting rings 360 instead of the metal inner rings 340 asshown.

Because the pipe 300 will be used offshore and subject to pressuredifferentials and low temperatures, it may be preferred to pre-stress orcompress the interior tubing 400 while assembling the rings 340/360thereon. In essence, the interior tubing 400 may be slightly overdiameter at normal temperatures. In this way, when subjected to lowtemperatures such as those experienced offshore, the interior tubing 400can remain engaged with the inside of the rings 340/360 even though thetubing 400 has shrunk or compressed due to temperature. One suitable wayto pre-stress or compress the interior tubing 400 during assemblyinvolves flowing cold water, liquid nitrogen, or the like through thetubing 400 itself or a conduit or tube disposed in the tubing 400. Thecold flow subjects the tubing 400 to low temperature while the rings340/360 and clamps 380 are assembled on the outside of the tubing 400.Alternatively, the tubing 400 can be designed to not react significantlyto the expected low temperature ranges that it may experience.

Eventually, an end of the interior tubing 400 is reached so the pipesection 302 can be prepared to receive components of the flanged end304. Towards the end of interior tubing 400, an end ring 350 first fitsonto the interior tubing 400 and abuts against the last intermediatering 360 and inner ring 340. This end ring 350 can be essentially thesame as the intermediate rings 360, but may have a greater length.

With the interior tubing, rings, and clamps of the pipe section 302done, the exterior tubing 450 is then positioned along the length of theassembly to complete the pipe section 302. In general, the exteriortubing 450 can have one or more outer layers. As shown in the end viewof FIG. 9C, for example, the exterior tubing 450 has three outer layers452, 454, and 456, although any number of layers could be used dependingon the implementation.

Like the interior tubing 400, this exterior tubing 450 can also be aspoolable reinforced composite (SRC) pipe similar to that available fromFuture Pipe Industries. The first outer layer 452 can be an extrudedthermoplastic liner and can have a suitable wall thickness, while thesecond outer layer 454 can be an overwrapping of composite laminate. Thethird outer layer 456 is preferably an external jacket composed of amaterial with a thickness suitable for the environment (i.e., offshore)in which the pipe 300 will be exposed.

The exterior tubing 450 can be pre-constructed piping that is pulledalong the length of the assembled rings 340/350/360 and clamps 380 usingtechniques known in the art. Alternatively, the separate layers of theexterior tubing 450 can be successively formed along the length of theassembly. For example, the first layer 452 of thermoplastic liner can beextruded or formed along the length of the assembly using techniquesavailable in the art. Then, the second layer 454 can be formed as anoverwrapping of composite material that is subsequently surrounded bythe outer jacket of the third layer 456. Preferably, the series of rings350/360 and clamps 380 are flush on their exterior surfaces to provide acontinuous cylindrical outside surface for engaging inside thesurrounding exterior tubing 450.

With the exterior tubing 450 completed, the flanged end 304 can beassembled on the end of the pipe section 302. Exposed ends of theinterior and exterior tubing 400 and 450 are cut to proper lengths toaccommodate the components of the flanged end 304. Initially, theinterior tubular support 320 fits inside the bore of the interior tubing400, and the outer tubular support 330 is disposed on the exteriortubing 450 for later assembly. Then, an inner ring 340 fits on theinterior tubing's exposed end and abuts the inside of the end ring 350.

At this point, the flange 310 fits on the exposed end of the interiortubing 400 so that it abuts against the end ring 350 and last inner ring340. To hold the flange 310, the end clamp 370 couples the flange 310 tothe end ring 350. As shown in FIG. 8B, this end clamp 370 can be thickerthan the intermediate clamps 380 used between the rings 350/360.Alternatively, this end clamp 370 may not be as thick as shown in FIG.8B, although it may be wider. In this way, the abutting ends of theflange 310 and end ring 350 can be thicker and more reinforced thandepicted in FIG. 8B.

When the flange 310 is installed, an inside groove of the flange 310abuts against the end of the inner tubular support 320, and O-ring seals307 inside grooves in the flange 310 seal against the outside of theinterior tubing 400. As shown, the distal end of the inner support 320extends beyond the distal end of the flange 310 and sandwiches thelayers of the interior tubing 400 inside the flange 310 and portion ofthe end ring 350. For additional support, this inner tubular support 320can extend a further distance inside the flange 310 towards its opening.

To complete the flanged end 304, the outer tubular support 330previously positioned on the exterior tubing 450 then threads onto theoutside of the flange 310. Once threaded, the exterior support 330extends from the flange 310 and sandwiches layers of the exterior tubing450 between the end ring 350 and portion of the last intermediate ring360. To help with sealing, first O-ring seals 306 seal the engagement ofthe support 330 with the flange 310, and second O-ring seals 308 sealthe engagement of the support 330 with the exterior tubing 450.

At this point, the construction of the flexible pipe 300 in FIGS. 8A-8Bis practically complete, and the other end of the pipe section 302 canbe constructed with another flanged end 304 in the same manner describedpreviously. With an understanding of the components of the flexible pipe300 described above, the discussion now turns to some particular detailsof the various components.

2. End Flange

The flange 310 shown in more detail in FIGS. 10A-10B is preferablycomposed of metal, such as 4140 steel, or other suitable material. Theflange 310 has an internal passage 312 for conducting fluid (such asoffshore production fluid). One end of the flange 316 is configured witha circumferential channel 317 for coupling to an end ring (350) via anend clamp (370) as discussed previously. As depicted, the other end 314of the flange 310 can be designed to couple using a Grayloc® remotelyoperated connector. (GRAYLOC is a registered trademark of GraylocProducts, LLC). Of course, the flange 310 can be configured to couple toa hub or other offshore production equipment using any availabletechniques known in the art.

Inside the bore 312, a ledge 313 supports an end of the inner support(320) that disposes in the bore 312. Also, slots 311 hold O-ring seals(not shown) for engaging the interior tubing (400) that disposes in thebore 312. Externally, the flange 310 has a threaded section 318 forcoupling to the outer support (330), and slots 319 hold O-ring seals(not shown) for engaging the outer support (330) when disposed on theflange's second end 316.

3. Inner & Outer Supports

The inner support 320 shown in more detail in FIG. 11 is preferablycomposed of metal, such as 4140 steel, or other suitable material. Thesupport 320 has an elongated, tubular body with a bore 322 forconducting fluid. The support's first end 324 fits against the flange'sledge (313), whereas the second end 326 is intended to fit inside thebore of the interior tubing (400). Both of the bore's internal edges atthese ends 324/326 are beveled to facilitate fluid flow through thesupport 330.

The outer support 330 shown in more detail in FIG. 12 is preferablycomposed of metal, such as 4140 steel, or other suitable material. Theouter support 330 has a tubular body with a bore 332 for fitting on theend of the flange (310) and part of the exterior tubing (450). Inside,the bore 322 has threading 334 for mating to the flange (310), while thesecond end 336 has slots 338 to hold O-ring seals (not shown)to engagethe exterior tubing (450).

4. Ring Configurations

As noted above, the flexible pipe 300 of FIGS. 8A-8B has three types ofrings, including the inner rings 340, the end ring 350, and theintermediate ring 360. Each of the rings 340/350/360 can be composed ofthe same or different materials. In general, the rings 340/350/360 canbe composed of metal, such as 4140 steel, or other suitable material.

The inner ring 340 shown in more detail in FIG. 13 has an internal bore342 for fitting onto the pipe's interior tubing (400). Externally, thisring 340 has outer tapered surfaces 345 a-b that taper in opposingdirections from a center of the ring's outer surface to the opposingsides of the ring 340. Each of these tapered surfaces 345 a-b alsodefines a slot 346 for holding an O-ring seal (not shown) to engage asurface of an abutting ring (350, 360) as discussed herein.

The end ring 350 shown in more detail in FIGS. 14A-14B also has aninternal bore 352 for fitting onto the pipe's interior tubing (400). Afirst end 354 abuts the end flange (310) and has a channel 357 to clampthereto with an end clamp (370). Similarly, the second end 356 abuts anintermediate ring (360) and has a similar channel 357 to clamp theretowith an intermediate clamp (380).

As shown in FIG. 14B, each channel 357 at the ends 354/356 may have aninternal shoulder that is less than perpendicular to the central axis ofthe ring 350. In particular, the internal shoulder can define an angleθ₂ of about 88-degrees or so (i.e., slanting inward about 2-degrees orso from perpendicular). As noted below, this angle θ₂ mirrors what isused for the clamps (370, 380) used to couple in the channel 357. (Forconsistency, the flange 310 in FIG. 10A uses the same angle θ₂ for theinside shoulder of its channel 317.)

As shown in FIG. 14A, the bore 352 has beveled edges 355 a-b at thefirst and second ends 354/356 for abutting against inner rings (340) andsealing with the O-ring seals (not shown) disposed on the rings (340).As shown in FIG. 14B, these edges can define an angle θ₁ of about10-degrees or so, which can match the taper of the inner ring's outersurfaces (345 a-b). (The beveled edge 315 in FIG. 10A for the flange 310can also be similarly angled.)

The intermediate ring 360 is shown in more detail in FIG. 15 and issimilarly configured to the end ring (350) with the exception of havinga shorter axial length. Therefore, like reference numerals are used forsimilar elements in these two rings 350/360. Advantageously, the bevelededges 355 a-b/ 365 a-b facilitate fitting the rings (350/360) on theinterior tubing (400) during assembly by making sliding the rings on thetubing easier.

In general, the internal bores 342/352/362 of these rings 340/350/360can have a diameter to accommodate interior tubing (400). For example,the tubing (400) can have a diameter of about 4 to 12-in. and can have awall thickness that depends on the implementation. For interior tubing(400) having an outside diameter of about 4.5-in., the end ring 350 canhave an axial length of about 6-in., while the intermediate ring 360 canhave an axial length of about 3-in. These dimensions are illustrativeand can vary depending on the requirements of a given implementation andespecially depend on the desired size of the pipe.

5. Flange, Ring, and Clamp Engagement

As noted above, an end clamp 370 shown in FIG. 9B is used to clamp theabutting end ring 350 to the flange 310, and intermediate clamps 380 inFIG. 9B are used to clamp the abutting rings 350/360 together. Each ofthe clamps 370/380 can be composed of the same or different materials.In general, the clamps 370/380 can be composed of metal, such as 4140steel, or other suitable material. Moreover, the clamps 370/380 may becomposed of the same or different material than that used for the rings340/350/360. Having rings and clamps of various materials enables thepipe 300 to be particularly configured for tensile strength, pressurerating, amount of achievable flexure, and other factors for a particularimplementation.

The end clamp 370 shown in detail in FIGS. 16A-16F has outer lips 374and a center groove 372 defined inside its circumference. The lips 374respectively fit into a channel (317) on the flange (310) and a channel(357) on the end ring (350) to coupled them together. The internalshoulders 378 of these lips 374 as shown in FIG. 16E can define an angleθ₃ of about 88-degrees or so (i.e., slanted inwards about 2-degrees) tomatch the angle used on the channels discussed previously. Using theseangled shoulders 376 on the lips 374 and the shoulders in the channels(317, 357) helps the end clamp 370 to interlock with the adjoining endring 350 and flange 310.

As shown, the end clamp 370 defines a half circle. One end of the clamp370 has an internal facing notch 376, while another end has an externalfacing notch 378. These notches 376/378 can have a tongue and groovearrangement that snap fits together in a clipping action when positionedon the rings. Two of the end clamp 370 shown in FIG. 16A couple togetherto clamp the flange (310) and end ring (350) together. This is bestshown in FIG. 9B, which shows an isolated view of the rings (340, 350,360) and clamps (370, 380). Accordingly, coupling two of the end clamps370 together to clamp rings together involves fitting the clamps 370 onopposing sides of the abutting ring 350 and flange 310, matting theopposite facing notches 376/378 on the two clamps 370 together, andfastening the notches together with bolts or the like through fastenerholes 371.

The intermediate clamp 380 shown in detail in FIGS. 17A-17D is similarto the end clamp (370) discussed previously with the exception of beingthinner. Therefore, like reference numerals are used for similarelements in these two rings 350/360. In one implementation, the endclamp 370 defines an inner radius of about 5.5-in. when used forinterior tubing (400) having an outside diameter of about 4.5-in. Theintermediate clamp 380 similarly defines an inner radius of about5.5-in.

An alternative form for coupling the clamps 370/380 together is shown indetail in FIGS. 18A-18D. Here, a clamp 375 (which can be an end orintermediate clamp) has holes 373 formed tangentially in an end forreceiving fasteners (e.g., bolts) to couple in complementary holes on anend of another such clamp 375. Thus, fasteners couple these clamps 375together in a tangential arrangement, while the fasteners for thepreviously described clamps 370/380 couple them together in aperpendicular arrangement.

Yet another clamp 385 shown in detail in FIGS. 19A-19C is configured tofit together using the notches on the ends without using fasteners andholes as in previous clamps. This clamp 385 may be suitable for theintermediate clamps used for the pipe 300. Having the interconnectingnotched ends remain unfastened may allow these clamps 385 to shift oradjust relative to one another while affixing abutting rings together,and this degree of free-play may facilitate the bending or flexing ofthe pipe section 302 as discussed herein.

Although the various clamps 370/375/380/385 discussed above form a halfcircle so that two such clamps affix together to clamp abutting ringstogether, it will be appreciated that the clamps may define a smallercircumference so that more than two such clamps may be affix together toclamp the abutting rings together. For example, FIG. 20A shows threeclamps 390 that fit together around abutting rings (not shown) to affixthem together. These clamps 390 may have similarly notched ends and mayor may not use fasteners.

If clamps used for the assembly are composed of a suitably flexiblematerial and thickness, another alternative clamp can be composed of aunitary piece defining a full circle that can be opened and fit aroundthe circumference of the rings so the clamp's ends can then be affixedtogether to clamp the rings together. For example, FIG. 20B shows aclamp 395 composed of a unitary circle with a slit. This clamp 395 canflex open and fit around abutting rings (not shown), and the clamp'sends can couple together to affix the abutting rings to one another. Asbefore, the clamp 395 may have similarly notched ends and may or may notuse fasteners. The above-described clamps and other possibilities willbe evident to one skilled in the art having the benefit of the presentdisclosure.

6. Bending and Flexing of Flexible Pipe

As noted previously, the flexible pipe 300 is used to conduct productionfluid offshore. Although the pipe 300 has rings 340/350/360 and clamps370/380 composed of metal, the pipe 300 can be relatively buoyant due tothe interior and exterior tubing 400/450. This is advantageous inoffshore applications where long lengths of the pipe 300 can be used inseawater.

In the offshore environment, the pipe 300 must be able to be bent so itcan be connected between offshore equipment. Moreover, deploying thepipe 300 offshore may require the pipe to be spooled on a reel carriedby a deployment vessel. In addition, the pipe 300 must be able to flexso it can handle movement caused by offshore currents and the like.

To illustrate the capabilities of the pipe 300, FIG. 21 shows an examplesection of the flexible pipe 300 in a bent or flexed state. In onearrangement, the rings 340/350/360 and clamps 370/350 with theassociated interior and exterior tubing 400/450 discussed above enablethe pipe 300 to bend or flex at about ½-degree for every length ofintermediate ring 350, although other degrees of bending and flexing canbe configured for a particular implementation. Because the layers forthe tubing 400/450 are composed of materials such as plastic,fiberglass, composites, etc., they can readily flex with the bending ofthe pipe 300.

During the bending or flexing, the seals 348 on the outside of the innerrings 340 remain sealably engaged with the beveled ends of the abuttingrings 360. The clamps 380 hold the abutting rings 360 together with theinwardly angled shoulders on the inside of the clamps 380 and the ring'schannels helping to interlock the clamps 380 with the rings 360 evenwhile slightly pivoted relative to one another.

Slight gaps purposefully configured by the dimensions of the componentsallow the abutting rings 360 held by the clamps 380 to pivot relative toone another. In particular, as shown in the detail of FIG. 22A, gaps G1are provided between the shoulders at the clamp 380 and the channels ofthe abutting rings 360. In a bent state such as shown in FIG. 22B, thesegaps G1 allow for movement of one ring 360 relative to the other byproducing other gaps G2, while the clamp's shoulders 387 interlock withthe channel's shoulders 367. In addition, the split in the inner ring340 may allow these rings 340 to accommodate movement of the adjacentrings 350. All the while, the seals 348 on the inner ring 340 maintainsealed engagement with the beveled ends of the adjoining rings 360.

The foregoing description of preferred and other embodiments is notintended to limit or restrict the scope or applicability of theinventive concepts conceived of by the Applicants. The presentdisclosure has described the flexible pipes for use offshore to conductoffshore production fluids. It will be appreciated with the benefit ofthe present disclosure, however, that the flexible pipes disclosedherein can be used in other applications. For example, features of thepipe's layers such as the materials used, the arrangement of the layers,their thicknesses, their internal diameters, and the like can beconfigured for a particular implementation. In addition, the pipe'sflexibility, reduced maintenance, lighter weight, and the like make thepipe suitable for land-based applications and gas transportation as wellas offshore applications.

In exchange for disclosing the inventive concepts contained herein, theApplicants desire all patent rights afforded by the appended claims.Therefore, it is intended that the appended claims include allmodifications and alterations to the full extent that they come withinthe scope of the following claims or the equivalents thereof.

1. A flexible pipe, comprising: interior tubing having one or more firstlayers and defining a bore for conducting fluid; a plurality of firstrings disposed about the interior tubing, each of the first ringsabutting one another; a plurality of clamps coupling the abutting firstrings together; and exterior tubing having one or more second layers anddisposed about the first rings and the clamps.
 2. The pipe of claim 1,wherein each of the first rings comprises a separate ring disposedindependently on the interior tubing.
 3. The pipe of claim 1, whereineach of the clamps comprises a separate clamp disposed independently onthe first rings.
 4. The pipe of claim 1, wherein the flexible pipecomprises a jumper, a flow line, a riser, or conduit used in offshoreproduction.
 5. The pipe of claim 1, wherein the one or more first layersof the interior tubing comprise: an inner liner having the bore forconducing fluid; and at least one outer layer disposed about the innerliner.
 6. The pipe of claim 5, wherein the at least one outer layercomprises an overwrapping layer of a composite laminate.
 7. The pipe ofclaim 1, wherein the one or more second layers of the exterior tubingcomprises: an inner layer disposed on the plurality of rings and clamps;and an overwrapping layer of a composite laminate disposed about theinner layer.
 8. The pipe of claim 1, further comprising a flangeassembly coupled to an end of the pipe.
 9. The pipe of claim 8, whereinthe flange assembly comprises a flange having a distal end abutting oneof the first rings on the end of the pipe, and a second clamp couplingthe one first ring to the distal end of the flange.
 10. The pipe ofclaim 8, wherein the flange assembly comprises an inner tubular supportdisposed inside the bore of the interior tubing and having one endengaging inside a bore of the flange.
 11. The pipe of claim 8, whereinthe flange assembly comprises an outer tubular support disposed outsidethe exterior tubing and having one end coupled to the flange.
 12. Thepipe of claim 1, wherein each of the clamps comprises at least two clampportions fitting around the abutting first rings and coupling together.13. The pipe of claim 12, wherein each of the at least two clampportions has ends fastenable to ends of the other of the at least twoclamp portions.
 14. The pipe of claim 12, wherein each of the at leasttwo clamp portions has a first end with an interior-facing notch and asecond end with an exterior-facing notch, the first ends being mateablewith the second ends.
 15. The pipe of claim 1, wherein: the first ringseach define an opening fittable onto the interior tubing, each end ofthe opening defining an inner tapered surface; and the pipe furthercomprises a plurality of second rings disposing on the interior tubingbetween the first rings, each of the second rings having outer taperedsurfaces abuttable to one of the inner tapered surfaces of the firstrings.
 16. The pipe of claim 1, wherein the plurality of first rings andclamps permit pivoting between interconnected ones of the rings.
 17. Aflexible pipe assembly method, comprising: disposing a plurality offirst rings about interior tubing; abutting the first rings end-to-endon the interior tubing; clamping the first rings together end-to-end byaffixing a plurality of clamps to the abutting ends of the first rings;and disposing exterior tubing about the first rings and the clamps. 18.The method of claim 17, wherein disposing the first rings about theinterior tubing comprises disposing each of the first rings as anindependent ring on the interior tubing.
 19. The method of claim 17,wherein affixing a plurality of clamps to the abutting ends of the firstrings comprises disposing each of the clamps as an independent clamp onthe first rings.
 20. The method of claim 17, wherein disposing theexterior tubing about the first rings and the clamps comprises pullingthe exterior tubing over the first rings and clamps.
 21. The method ofclaim 17, wherein disposing the exterior tubing about the first ringsand the clamps comprises forming the exterior tubing over the firstrings and clamps.
 22. The method of claim 17, further comprising:disposing a plurality of second rings about the interior tubing betweenthe first rings; and abutting each of the second rings to a portion of abore in the ends of the first rings when abutting the first ringsend-to-end.
 23. The method of claim 19, wherein abutting each of thesecond rings to the portion of the bore in the ends of the first ringscomprises disposing seals between the first and second rings.
 24. Themethod of claim 17, wherein affixing the plurality of clamps to theabutting ends of the first rings comprises: fitting at least two clampportions in adjacent channels on the ends of the first rings; andaffixing notched ends of the at least two clamp portions together. 25.The method of claim 17, further comprising fitting a flange assembly onan end of the flexible pipe.
 26. The method of claim 25, wherein fittingthe flange assembly comprises: disposing a flange on an end of theinterior tubing; abutting an end of the flange against the first ring atthe end of the pipe; and clamping the flange and the first ring togetherend-to-end by affixing a clamp to the abutting ends of the flange andthe first ring.
 27. The method of claim 26, wherein fitting the flangeassembly comprises: disposing a first support in a first bore of theflange and a second bore of the interior tubing; and engaging the flangeto an end of the exterior tubing by disposing a second support outsidethe flange and the exterior tubing.